The theft of automobiles, boats, motorcycles, RVs, and like vehicles has prompted the creation of an endless assortment of anti-theft devices. The primary problem associated with most of these devices is that would-be thieves quickly ascertain a method to defeat the effectiveness of the device. In addition, many anti-theft devices are unreliable, poor in quality, high in cost, difficult to use or require considerable time by the user/installer to implement and maintain.
The majority of anti-theft devices can be classified into three basic categories. The first category includes devices which physically immobilize a vehicle component, such as a steering wheel, locking mechanisms and/or the transmission. "The Club".TM. is a prime example of a physical immobilization device. The second category involves intruder detection mechanisms which, upon intrusion, either actuate an alarm system (such as flashing lights, horn sounding, and the like) or otherwise disable an electrical system of the vehicle. The third category encompasses devices specifically directed to a method or apparatus for selectively enabling and disabling operational systems within the vehicle including, for example, the ignition, fuel systems, computer control systems, and similar electrical systems which are essential for proper operation of the vehicle. The present invention lies within this third category. More particularly, the present invention provides a security key system which enables specific electrical systems when a security key is properly introduced into the system, and disables the system when the key is removed therefrom.
The prior art is replete with methods and devices, such as security keys, for attempting to prevent theft or other unwanted access to automobiles and other vehicles. For example, U.S. Pat. No. 4,327,353 to Beard et al. provides for an electronic security system with an encoded security card. The card consists of a plurality of coded contacts on the upper side of the card. When the proper key is inserted into a female decoding reader it allows the system to function without tripping alarms.
U.S. Pat. No. 4,945,872 to Embry relates to a theft prevention apparatus comprising a disabling device for electronic circuits. The device includes a female connector and a male "key". The inwardly facing rear surface of the female connector features a plurality of outwardly projecting terminals for connection of electrical wires. The female connector is incorporated into the automobile ignition circuit by severing a predetermined group of wires. When the male connector is removed from the female connector, the vehicle is disabled. The device includes "dummy" wires to give false readings for tamper resistance.
U.S. Pat. No. 5,133,426 to Niriella et al. illustrates the use of anti-tamper circuitry wherein a security key is used to make various combinations of direct and indirect (i.e using relays) electrical circuit connections. Niriella et al. further provides for the use of false circuit connections not actually connected to electrical circuits.
U.S. Pat. No. 2,868,905 to Meyer discloses an electric lock intended for use as an ignition lock for an automotive vehicle which prevents unauthorized circuit closing. The device comprises a plurality of contacts, only predetermined ones of which close a desired circuit. The correct key will electrically connect the proper contacts.
The patent to Vandigriff (4,435,649) provides for a digital encoded key for an anti-theft circuit.
The patent to Vaughan et al. (4,871,886) illustrates a double-sided security key including a guide and biasing means.
The patent to Housman et al. (3,876,884) illustrates a double-sided security key with longitudinal contact connections. The key must be flipped over to use both sides.
The patent to Granholm et al. (4,298,792) provides for a security key with encoded contacts which is placed into a female receptor.
The patent to Jaulmes (4,331,013) provides for a two-sided magnetically encoded anti-theft security key which actuates switches located in a female receiving section.
The patent to Dimitriadis (3,797,936) provides for an electronic locking system with an encoded key having multiple encoding schemes.
The patent to Romano (4,755,799) illustrates a particular design of an electronic security card.
The present invention overcomes the deficiencies encountered in the prior art by providing a double sided security key not illustrated by the above prior art references. Further, the present double-sided security key employs unique coding structures which are concealed within the key for securely connecting one or more electrical circuits, unlike the Niriella and Embry patents noted above. Moreover, the present invention does not require various combinations of logic schemes, such as dummy wires, during the course of connecting electrical circuits, thereby creating false readings for anti-tamper purposes, which is the method of choice in Niriella and Embry.